C语言数据结构之链队列的基本操作

＃define  TRUE    1
＃define  FALSE  0
typedef struct QNode{
        QElemType  data;
        struct QNode *next;
}QNode, *QueuePtr;
typedef struct{
        QueuePtr  front;
        QueuePtr  rear;
}LinkQueue;

Status InitQueue(LinkQueue &Q)
{ 
       Q.front = Q.rear = (Queueptr) malloc(sizeof(QNode));
       if(!Q.front) exit ( OVERFLOW);
       Q.front ->next = NULL;
       return OK;
} 

Status DestroyQueue(LinkQueue &Q)
{ 
        while(Q.front) {
	Q.rear = Q.front->next;
	free (Q.front);
	Q.front = Q.rear;
        }
        return OK;
}

Status EnQueue (LinkQueue &Q, QelemType e)
{ 
        p= (QueuePtr) malloc(sizeof(QNode));
        if (!p) exit ( OVERFLOW);
        p->data = e;  p->next = NULL;
        Q.rear -> next =p;
        Q.rear = p;
        return OK;
}

Status DeQueue (LinkQueue &Q, QelemType &e)
{
        if ( Q.front == Q.rear) return ERROR;
        p=Q.front->next;
        e=p->data;
        Q.front->next =p->next;
        if (Q.rear == p) Q.rear = Q.front;
        free(p);
        return OK;
}

#include<iostream>
using namespace std;
#define OK 1
#define FALSE 0

typedef int QElemType;
typedef int Status;

typedef struct QNode{
    QElemType data;
    struct QNode *next;
}QNode,*QueuePtr;
typedef struct{
    QueuePtr font;
    QueuePtr near;
}LinkQueue;

Status InitQueue(LinkQueue &Q)
{
    Q.font=(QueuePtr)malloc(sizeof(QNode));
    if(!Q.font) exit(FALSE);
    Q.font->next=NULL;
    Q.near=Q.font;
    return OK;
}
Status QueueEmpty(LinkQueue Q)
{
    if(Q.font->next) return OK;
    return FALSE;
}
Status EnQueue(LinkQueue &Q,QElemType e)
{
    QueuePtr p=(QueuePtr)malloc(sizeof(QNode));
    p->data=e;
    Q.near->next = p;
    Q.near = Q.near->next;
    p->next = NULL;
    return OK;
}
Status DeQueue(LinkQueue &Q,QElemType &e)
{
    if(!Q.font->next) return FALSE;
    QueuePtr p;
    p=Q.font->next;
    e=p->data;
    Q.font->next=p->next;
    if(Q.near==p) Q.near=Q.font;   //当是最后一个元素时，Q.font=NULL,Q.near=Q.font
    free(p);
    return OK;
}
Status ClearQueue(LinkQueue &Q)
{
    QueuePtr p;
    p=Q.font->next;
    QueuePtr q;
    while(p)
    {
        q=p;
        p=p->next;
        Q.font->next=p;
        free(q);
    }
    Q.near=Q.font;
    return OK;
}
void menu()
{
    cout<<"初始化队列:1"<<endl;
    cout<<"入队:2"<<endl;
    cout<<"出队:3"<<endl;
    cout<<"清空队列:4"<<endl;
    cout<<"退出:5"<<endl;
}
int main()
{
    LinkQueue Q;
    while(true)
    {
        int n;
        menu();
        scanf("%d",&n);
        int e=-1;
        switch(n)
        {
            case 1:
                InitQueue(Q);
                continue;
            case 2:
                printf("请输入一个元素");
                scanf("%d",&e);
                EnQueue(Q,e);
                continue;
            case 3:
                DeQueue(Q,e);
                printf("\n出队元素%d\n",e);
                continue;
            case 4:
                ClearQueue(Q);
                printf("清空成功\n");
                continue;
            default:
                break;
        }
        if(n==5)break;
    }

}